NEW WINDOWS | Glance at the surface of Longhorn, and it seems like a reinvention of fatware. The flashiest part, the Avalon graphics subsystem, is such a hog that Microsoft admits you’ll need a hardware upgrade to get the full effect of its rich new 3-D GUI that will supposedly knock you out of your chair.

But Avalon’s pizzazz starts to seem like a diversion when you pop the hood on Longhorn and peer inside. There’s so much Internet and messaging code in there, I’m convinced that Microsoft has laid the foundation to end the distinction between client and server.

WS-Everything

Consider the three new technology pillars that underlie Longhorn: Avalon, the WinFS storage system and Indigo. The most interesting is Indigo, a big stack of draft Web services protocols (such as WS-Security, WS-Federation, WS-ReliableMessaging, WS-Coordination and more) introduced by Microsoft and various partners that together will function as a kind of pure, Web services-based middleware with peer-to-peer functionality as well as connections to desktop apps.

In other words, all Longhorn applications can be Internet applications integrated into the rest of the enterprise because the connective tissue is woven into the platform. Flip a switch, and a desktop spreadsheet, for instance, could become a Web services application. The vexing problem that has dogged the PC since birth?too much data locked in desktops?is on the verge of being solved, because every desktop will also be a server.

A key element in desktops becoming good enterprise citizens is WinFS, which will stipulate an XML-based storage system for desktop data. (Contrary to rumor, WinFS doesn’t replace NTFS; it runs on top of it.) This common XML denominator will make desktop content easier to expose and consume.

WinFS will also help desktop applications communicate with each other. For example, why shouldn’t meta-data from your e-mail client?whom you e-mail most often, the folders you browse frequently?be used to rank desktop search results? Mail clients built on WinFS and its open XML interfaces raise that possibility.

XML at the Core

Are we starting to see a pattern here? XML is Longhorn’s middle name. In the end, XML drives even Avalon. Along with enabling fancy 3-D tricks, Avalon comes with a new way to describe GUIs: XML application markup language (XAML?not to be confused with the old B2B play by IBM, Oracle and others known as the Transaction Authority Markup Language). Microsoft claims it learned from the simplicity of Web development and says that coding GUIs for Longhorn apps will be much easier than in earlier Windows versions. XAML also lets designers create GUIs using tools they already know. For example, Adobe has demoed an alpha version of its After Effects app that spits out XAML code.